Unprotected sexual intercourse between men constitutes 58% of all reported cases of AIDS and 80% of HIV cases 1,2. Rates of HIV infection among 15 to 24 year olds continue to increase with MSM behavior remaining the leading cause of HIV infection among adolescent males 1,2. Over 90% of YMSM have reported having more than one sexual partner in the past 6 months and between 33% and 49% have had unprotected anal intercourse during the same time3. Studies show that use of stimulants, particularly methamphetamine, may influence risky sexual practices and contribute to the most recent wave of HIV and other sexually transmitted infections (STIs)4-6. Systematic development of theory has been identified as a crucial step in efficacious intervention development, but previous conceptual models have focused on a relatively limited array of explanatory constructs. However, Social Action Theory (SAT)7 provides a promising model for examining the risk behavior of YMSM, because it includes individual as well as social and contextual determinants. SAT remains to be tested for use in the field of HIV and with YMSM, because this model was originally conceived as a general health promotion model for the adult population. Using data from the Dr. Kipke's NIDA funded "Healthy Young Men Study" (HYM), this study will conduct multivariate analysis to test this model for use with the YMSM population. The specific aims of this study are to: 1) To empirically validate the chain of relationships depicted in Social Action Theory to determine if the theory addresses the interaction of individual, contextual, and social correlates of sexual and drug risk taking behaviors as they relate to YMSM; and 2) To further validate SAT by testing and incorporating competing theoretical relationships depicted in other behavioral theory models to develop a comprehensive theory of the social, psychosocial and cognitive risk factors for drug use, sexual impulsivity, and HIV among YMSM to guide prevention intervention efforts. . This study will contribute to the objectives of the AIDS-Science Track Award for Research Transition by 1) supporting a New Researcher; 2) addressing the NIDA research objective in the area of HIV, drug abuse, impulsivity, and coping strategies of an at-risk, under represented population; and 3) through refinement of a comprehensive theoretical model, we will provide a platform for developing interventions that address risk behavior related to HIV transmission among YMSM. PUBLIC HEALTH RELEVANCE: This study will contribute to effective HIV interventions for at-risk youth by developing a model to understand how environmental risk factors, impulsivity, and coping strategies converge into drug abuse and sexual risk taking. [unreadable] [unreadable] [unreadable]